Changing a master node in a wired local area network and related systems, methods, and devices

ABSTRACT

Various embodiments relate to a wired local area network (WLAN) including a shared transmission medium (e.g., a 10SPE network). A method may include detecting an event in a WLAN including physical level collision avoidance (PLCA). The method may also include disabling a beacon of a first node operating as a master of the WLAN in response to the event. Further, the method may include enabling a second node to operate as the master of the WLAN.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/838,750, which was filed on Apr. 25, 2019, the entire disclosureof which is hereby incorporated herein by this reference.

FIELD

The present disclosure relates, generally, to management of nodemastership in a network, and more specifically to changing of a masternode in a wired local area network.

BACKGROUND

Various interface standards for connecting computers and externalperipherals may be used to provide connectivity at high speeds. A widelyused, flexible networking standard for connecting computers (e.g., inLocal Area Networks (LANs) and Wide Area Networks (WANs)) is theEthernet protocol. Ethernet communication generally refers topoint-to-point communication within a network of multiple end points.Ethernet generally makes efficient use of shared resources, is easy tomaintain and reconfigure, and is compatible across many systems.

BRIEF DESCRIPTION OF THE DRAWINGS

While this disclosure concludes with claims particularly pointing outand distinctly claiming specific embodiments, various features andadvantages of embodiments within the scope of this disclosure may bemore readily ascertained from the following description when read inconjunction with the accompanying drawings, in which:

FIG. 1 is a functional block diagram of a network segment, according tosome embodiments;

FIG. 2 depicts a number of bus cycles for a line of a physical levelcollision avoidance (PLCA) sublayer, according to some embodiments;

FIG. 3 depicts another bus cycle for a line of a PLCA sublayer,according to some embodiments;

FIG. 4 illustrates a signal timing diagram associated with a second buscycle shown in FIG. 2, according to some embodiments

FIG. 5 depicts a network including a number of nodes;

FIG. 6 depicts a system including a network and a node;

FIG. 7 is a block diagram of an example of a physical layer device (PHY)of FIG. 6, according to some embodiments;

FIG. 8 is a flowchart illustrating an example method of operating anetwork such as a 10SPE network;

FIG. 9 is a flowchart illustrating an example method of operating anetwork node, according to some embodiments;

FIG. 10 depicts a vehicle including a network; and

FIG. 11 is a block diagram of a computing device that may be used insome embodiments.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof, and in which are shown,by way of illustration, specific examples of embodiments in which thepresent disclosure may be practiced. These embodiments are described insufficient detail to enable a person of ordinary skill in the art topractice the present disclosure. However, other embodiments may beutilized, and structural, material, and process changes may be madewithout departing from the scope of the disclosure.

The illustrations presented herein are not meant to be actual views ofany particular method, system, device, or structure, but are merelyidealized representations that are employed to describe the embodimentsof the present disclosure. The drawings presented herein are notnecessarily drawn to scale. Similar structures or components in thevarious drawings may retain the same or similar numbering for theconvenience of the reader; however, the similarity in numbering does notmean that the structures or components are necessarily identical insize, composition, configuration, or any other property.

The following description may include examples to help enable one ofordinary skill in the art to practice the disclosed embodiments. The useof the terms “exemplary,” “by example,” and “for example,” means thatthe related description is explanatory, and though the scope of thedisclosure is intended to encompass the examples and legal equivalents,the use of such terms is not intended to limit the scope of anembodiment or this disclosure to the specified components, steps,features, functions, or the like.

It will be readily understood that the components of the embodiments asgenerally described herein and illustrated in the drawing could bearranged and designed in a wide variety of different configurations.Thus, the following description of various embodiments is not intendedto limit the scope of the present disclosure, but is merelyrepresentative of various embodiments. While the various aspects of theembodiments may be presented in drawings, the drawings are notnecessarily drawn to scale unless specifically indicated.

Furthermore, specific implementations shown and described are onlyexamples and should not be construed as the only way to implement thepresent disclosure unless specified otherwise herein. Elements,circuits, and functions may be shown in block diagram form in order notto obscure the present disclosure in unnecessary detail. Conversely,specific implementations shown and described are exemplary only andshould not be construed as the only way to implement the presentdisclosure unless specified otherwise herein. Additionally, blockdefinitions and partitioning of logic between various blocks isexemplary of a specific implementation. It will be readily apparent toone of ordinary skill in the art that the present disclosure may bepracticed by numerous other partitioning solutions. For the most part,details concerning timing considerations and the like have been omittedwhere such details are not necessary to obtain a complete understandingof the present disclosure and are within the abilities of persons ofordinary skill in the relevant art.

Those of ordinary skill in the art would understand that information andsignals may be represented using any of a variety of differenttechnologies and techniques. Some drawings may illustrate signals as asingle signal for clarity of presentation and description. It will beunderstood by a person of ordinary skill in the art that the signal mayrepresent a bus of signals, wherein the bus may have a variety of bitwidths and the present disclosure may be implemented on any number ofdata signals including a single data signal.

The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein may be implementedor performed with a general purpose processor, a special purposeprocessor, a Digital signal Processor (DSP), an Integrated Circuit (IC),an Application Specific Integrated Circuit (ASIC), a Field ProgrammableGate Array (FPGA) or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor (may also be referred to herein as a hostprocessor or simply a host) may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, such as a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration. A general-purpose computer including a processor isconsidered a special-purpose computer while the general-purpose computeris configured to execute computing instructions (e.g., software code)related to embodiments of the present disclosure.

The embodiments may be described in terms of a process that is depictedas a flowchart, a flow diagram, a structure diagram, or a block diagram.Although a flowchart may describe operational acts as a sequentialprocess, many of these acts can be performed in another sequence, inparallel, or substantially concurrently. In addition, the order of theacts may be re-arranged. A process may correspond to a method, a thread,a function, a procedure, a subroutine, a subprogram, etc. Furthermore,the methods disclosed herein may be implemented in hardware, software,or both. If implemented in software, the functions may be stored ortransmitted as one or more instructions or code on computer-readablemedia. Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another.

Any reference to an element herein using a designation such as “first,”“second,” and so forth does not limit the quantity or order of thoseelements, unless such limitation is explicitly stated. Rather, thesedesignations may be used herein as a convenient method of distinguishingbetween two or more elements or instances of an element. Thus, areference to first and second elements does not mean that only twoelements may be employed there or that the first element must precedethe second element in some manner. In addition, unless stated otherwise,a set of elements may comprise one or more elements.

As used herein, the term “substantially” in reference to a givenparameter, property, or condition means and includes to a degree thatone of ordinary skill in the art would understand that the givenparameter, property, or condition is met with a small degree ofvariance, such as, for example, within acceptable manufacturingtolerances. By way of example, depending on the particular parameter,property, or condition that is substantially met, the parameter,property, or condition may be at least 90% met, at least 95% met, oreven at least 99% met.

A vehicle, such as an automobile, a truck, a bus, a ship, and/or anaircraft, may include a vehicle communication network. The complexity ofa vehicle communication network may vary depending on a number ofelectronic devices within the network. For example, an advanced vehiclecommunication network may include various control modules for, forexample, engine control, transmission control, safety control (e.g.,antilock braking), and emissions control. To support these modules, theautomotive industry relies on various communication protocols.

10SPE (i.e., 10 Mbps Single Pair Ethernet) is a network technologycurrently under specification development as IEEE 802.3cg™. 10SPE may beused to provide a collision free, deterministic transmission on amulti-drop network. The 10SPE specification intends to include anoptional physical level collision avoidance (PLCA) reconciliationsublayer, which is used to avoid physical collision on a multi-drop bus.PLCA relies on a master node, i.e. a PLCA master node, that sends out abeacon that starts a bus cycle, which is shared among multi-drop nodesin a round robin fashion. However, if the master nodes fails, alltraffic on a bus comes to a halt and the bus becomes unusable. Further,the 10SPE specification under development does not presently provide ameans to dynamically change a master of a network. The term “masternode” refers to a node with node identification of zero (0), and theterm “slave node” refers to a node with node identification greater thanzero (0).

Various embodiments relate to changing a master node of a network, andmore specifically to enabling a fallback master node in a network (e.g.,a wired local area network such as a 10SPE network). More specifically,various embodiments may relate to disabling a master node of the network(e.g., in response to one or more events and/or conditions) andreplacing the previous master node with a new master node (e.g., inresponse to a detection that the master node is not transmitting beaconsat an adequate frequency). In other words, a first node, which isoperating as a master node may fail and/or may be disabled (e.g., forone or more reasons such as a triggering of an airbag during a vehiclecollision), and another node, which was previously operating as a slavenode, may become the master node.

In some embodiments, a physical layer (PHY) (e.g., of a slave node) mayimplement a beacon counter. Firmware of the PHY may periodically readthe beacon counter. If there is no change to a count of the beaconcounter (or the count is less than an expected (e.g., threshold) count,it may be determined that the master node is disabled, broken, and/orlost. In this case, a fallback master node may be enabled (e.g., viafirmware), and the network may be resynced.

In some embodiments, a 10SPE PHY device may be used with amicrocontroller unit (MCU) configured to write to and/or read from the10SPE PHY device using a management data input/output (MDIO) interface.According to various embodiments, a slave node on a multi-drop networkmay maintain a count (e.g., via a counter) of beacons sent out by amaster node. Further, in some embodiments, firmware (FW) (e.g., in anMCU) may poll (e.g., periodically read) the value of the counter.According to some embodiments, the firmware may infer that the masternode has failed if the count value does not change at an expected rate.

In some embodiments, if it is determined that the master node has failedand/or the master node is disabled, firmware at a designated fallbackmaster node (e.g., a slave node) makes its PHY the PLCA master node.Further, the fallback master node may restart transmission of beacons onthe bus so that bus traffic can resume. To change master nodes, thefirmware at the current master node may cause the PHY of the currentmaster to stop its beacons (e.g., in response to a detection of an eventsuch as a vehicle collision, which may be signaled to the master nodewhen an airbag is deployed). This eventually causes the designatedfallback master to take over as the master node.

For example, if an emergency call (eCall) node is a fallback masternode, the mastership may be handed over to the eCall node. This might beneeded, for example, when a crash (e.g., a crash involving a vehicleincluding a 10SPE network) is detected (e.g., responsive to deploymentof an airbag). Various embodiments may be used to support eCall inresponse to detecting a crash (e.g., of a vehicle including a 10SPEnetwork). For example, master firmware disables the master node (e.g., anetwork node implemented in an amplifier device) of the network.Further, firmware of an eCall master node (e.g. firmware of a networknode implemented in an antenna or a microphone) may detect the lack ofincrease in a beacon count and resync a network by issuing beacons. TheeCall device (e.g. microphone) may be used to request assistance.

In some embodiments, firmware may control one or more (e.g., each) actsof a master change/exchange. Alternatively or additionally, one or moreacts of a change/exchange may be controlled by hardware.

The 10SPE specification under development presently includes a timer(e.g., in one or more nodes of a network) that may cause nodes to goinactive (i.e., a timeout) after a certain period of time has passedwithout an occurrence of a beacon. According to various embodiments, inresponse to one or more timeouts, a fallback master node may assume themaster role and resynchronize the bus. In these embodiments, it may notbe necessary for one or more messages to be exchanged between a masternode and a fallback master node during a master change/exchange, andtherefore, a network may be more robust.

Various embodiments of the present disclosure are now explained withreference to the accompanying drawings.

FIG. 1 is a functional block diagram of a network segment 100 includinga link layer device, MAC 104 and a physical layer (PHY) device, PHY 102,according to some embodiments. As non-limiting examples, network segment100 may be a segment of a multidrop network, a segment of a multidropsub-network, a segment of a mixed media network, or a combinationthereof or sub combination thereof. As non-limiting examples, networksegment 100 may be, be part of, or include one or more of amicrocontroller-type embedded system, a user-type computer, a computerserver, a notebook computer, a tablet, a handheld device, a mobiledevice, a wireless earbud device or headphone device, a wired earbud orheadphone device, an appliance sub-system, lighting sub-system, soundsub-system, building control systems, residential monitoring system(e.g., for security or utility usage, without limitation) system,elevator system or sub-system, public transit control system (e.g., forabove ground train, below ground train, trolley, or bus, withoutlimitation), an automobile system or automobile sub-system, or anindustrial control system, without limitation.

PHY 102 may be configured to interface with MAC 104. As non-limitingexamples, PHY 102 and/or MAC 104 may be chip packages including memoryand/or logic configured for carrying out all or portions of embodimentsdescribed herein. As non-limiting examples, PHY 102 and MAC 104,respectively, may be implemented as separate chip packages or circuitry(e.g., integrated circuits) in a single chip package (e.g., asystem-in-a-package (SIP)).

PHY 102 also interfaces with shared transmission medium 106, a physicalmedium that is a communication path for nodes that are part of networksegment 100 or a network of which network segment 100 is a part,including nodes that include respective instances of PHY 102 and MAC104. As a non-limiting example, shared transmission medium 106 may be asingle twisted pair such as used for single pair Ethernet. Devices thatare on a baseband network (e.g., a multidrop network without limitation)share the same physical transmission medium, and typically use theentire bandwidth of that medium for transmission (stated another way, adigital signal used in baseband transmission occupies the entirebandwidth of the media). As a result, only one device on a basebandnetwork may transmit at a given instant. So, media access controlmethods are used to handle contention for shared transmission medium106.

In some embodiments a network node associated with the PHY 102 and theMAC 104 may be configured to operate as a master node configured toadminister network level tasks for the network. For example, the networknode may be configured to transmit beacon signals on the sharedtransmission medium 106 at the beginning of bus cycles, as discussedwith reference to FIG. 2, FIG. 3, and FIG. 4. Also, the network node maybe configured to operate as a slave node in the network while anothernetwork node operably coupled to the shared transmission medium 106operates as the master node. The network node may be configured tooperate as a backup master node in the event that a failure or loss ofthe master node occurs. The network node may be configured to detect thefailure or loss of the master node (e.g., while operating as the slavenode). In some embodiments, while the network node is operating as amaster node, the network node may terminate its operation as the masternode responsive to an event such as a vehicle collision or adetermination that a failure has occurred in its operation as the masternode, and another network node operably coupled to the sharedtransmission medium 106 may assume operation as the master noderesponsive to detecting a lack of beacons signaled on the sharedtransmission medium 106. In some embodiments, while the network node isoperating as a slave node, the network node may assume operation as themaster node responsive to a determination that a failure or loss of themaster node has occurred (e.g., responsive to detecting a lack ofbeacons signaled on the shared transmission medium 106).

FIG. 2 depicts a number of bus cycles 200 for a line 246 (e.g., theshared transmission medium 106 of FIG. 1) of a physical level collisionavoidance (PLCA) sublayer, according to some embodiments. Specifically,FIG. 2 illustrates a first bus cycle 248 and a second bus cycle 250. Thebus cycles 200 include a plurality of time slots 252 (e.g., time slot202 through time slot 232) of the line 246. The time slots 252 are eachlabeled with a number (e.g., 0, 1, 2, 3, 4, N, the number N being anumber one less than a number of network nodes) corresponding to one ofvarious network nodes (e.g., node 0, node 1, node 2, node 3, node 4, . .. node N) that is to communicate during the respective one of the timeslots 252. Also, FIG. 2 indicates whether the communication in each ofthe bus cycles 200 includes a beacon 238, silence 240, data 242, or acommit signal 244. For example, as shown in FIG. 2, a beacon 238 may besent by a node 0 (e.g., a master node) during each of time slot 202,time slot 204, and time slot 206. Also, silence 240 may be present onthe line 246 during each of time slot 208 through time slot 226 (i.e.,data is not transmitted during time slot 206 through time slot 226).Further, in time slot 232 a commit signal 244 may be sent (i.e., by anode 3 to, for example, capture the bus before sending a packet of data242). Data 242 may be sent during time slot 228 and time slot 230. Morespecifically, a node 1 may send data 242 during time slot 228, and anode 3 may send data 242 during time slot 230.

During each of the bus cycles 200, the master node (node 0) may send outa beacon 238, which is followed by one or more time slots 252 for eachof the nodes (node 0 through node N). As shown in FIG. 2, the first buscycle 248 includes the time slot 202 having the beacon 238 transmittedby node 0, then silence 240 for time slot 208 through time slot 214during which node 0 through node N remain silent (i.e., silence 240during time slot 208 corresponding to node 0, time slot 210corresponding to node 1, time slots 212 corresponding to nodes 2 to N−1,and time slot 214 corresponding to node N. It should be noted that whereeach of the nodes take only a minimum time slot length 236 during thebus cycle, as is the case with first bus cycle 248, the bus cycle willhave a minimum bus cycle length 234.

After the first bus cycle 248 the second bus cycle 250 may occur. Duringthe second bus cycle 250 the master node (e.g., node 0) may send outbeacon 238 during time slot 204, then silence 240 during time slot 216of minimum time slot length 236 corresponding to node zero. The secondbus cycle 250 includes data 242 transmitted by node 1 during time slot228, then silence 240 for time slot 218 corresponding to node 2. At timeslot 232 the second bus cycle 250 includes an idle signal 244 (e.g., tocapture the bus before sending a packet of data 242) followed by timeslot 230 carrying data 242, the idle signal 244 and data 242 transmittedby node 3. The second bus cycle 250 further includes silence 240transmitted during time slot 220 corresponding to node 4, time slots 222corresponding to nodes 5 to node N−1, and time slot 224 corresponding tonode N. An additional beacon 238 at time slot 206 and individual nodetransmissions starting with node zero at time slot 226 then followssecond bus cycle 250.

FIG. 3 depicts another bus cycle 300 for a line 246 of a PLCA sublayer,according to some embodiments. Similar to the bus cycles 200 of FIG. 2,the bus cycle 300 includes time slots 328 marked to indicate nodes andcontent of the time slots 328. The bus cycle 300 includes a beacon 238signaled in time slot 302 by a master node (e.g., node 0), an idlesignal 244 signaled in time slot 306 and data 242 signaled in time slot314 by node 0. The bus cycle 300 also includes a commit signal 244signaled in time slot 308 and data 242 signaled in time slot 316 bynode 1. The bus cycle 300 further includes a commit signal 244 and data242 signaled in time slots 310 and time slots 318, respectively, by eachof nodes 2 through N−1. Finally, bus cycle 300 includes a commit signal244 and data 242 signaled in time slot 312 and time slot 320,respectively, by node N. FIG. 3 also shows a time slot 304 and a timeslot 322 transmitting a beacon 238 and silence 240, respectively, of abus cycle following the bus cycle 300.

FIG. 3 illustrates a maximum bus cycle length 326 wherein a beacon 238is sent at a start of each cycle, and each node sends a commit signal244 and data 242. Assuming that each combination of commit signal 244and data 242 transmitted by nodes 1−N has a maximum time slot length324, a duration of the bus cycle 300 is a maximum bus cycle length 326.Accordingly, if a number of nodes is known, both a minimum bus cyclelength 234 (FIG. 2) and a maximum bus cycle length 326 (FIG. 3) may bedetermined.

Since each bus cycle is accompanied by one beacon 238, a number ofbeacon 238 signals may be counted over time and a determination may bemade as to whether a number of counted beacon 238 signals is consistentwith the minimum bus cycle length 234 and the maximum bus cycle length326. For example, if the counted number of beacon 238 signals countedover a given period of time is less than a number of bus cycles havingthe maximum bus cycle length 326 that would fit within the given periodof time, it may be determined that a problem has occurred. Accordingly,a fallback master node may take over as master node (e.g., withoutintervention by the previous master node).

FIG. 4 illustrates a signal timing diagram 400 associated with thesecond bus cycle 250 (e.g., of the PLCA sublayer) shown in FIG. 2,according to some embodiments. The signal timing diagram 400 illustratesline signals 424 on the line 246 of FIG. 2, node 1 signals 420, node 3signals 422, and current node identification signals (CUR_ID signals442) on a CUR_ID line 418. The node 1 signals 420 include transmitenable signals (TXEN signals 426) on a TXEN line 402, transmit datasignals (TXD signals 428) on a T×D line 404, carrier sense signals (CRSsignals 430) on a CRS line 406, and collision detect signals (COLsignals 432) on a COL line 408. Similarly, the node 3 signals 422include TXEN signals 434 on a TXEN line 410, TXD signals 436 on a T×Dline 412, CRS signals 438 on a CRS line 414, and COL signals 440 on aCOL line 416. The CUR_ID signals 442 indicate an identificationindicating which of the nodes (e.g., node 0 through node 7) isdesignated to transmit data 242 on the line 246.

As illustrated in FIG. 4, following a previous bus cycle (e.g., firstbus cycle 248) finishing with a node 7 designated by the CUR_ID signals442 on the CUR_ID line 418, node 0 sends a beacon 238 on the line 246.Following a designation by the CUR_ID signals 442 on the CUR_ID line 418of node 0 to transmit on the line 246, the CUR_ID signals 442 indicatesnode 1, and node 1 sends data 242 on the line 246. While node 1 issending the data 242 on the line 246, node 3 attempts to send data 242on the line 246. Since node 1 is currently sending data 242 on the line246, however, a logical collision results (i.e., COL signals 440associated with node 3 transitions high and a jam signal 444 is assertedin the TXD signals 436 of T×D line 412). While the CRS signal 438 of theCRS line 414 of node 3 remain high, node 1 finishes sending the data 242on the line 246, and the CUR_ID signals 442 then indicates node 2.Subsequently, the CUR_ID signals 442 indicate node 3. Subsequently, theCRS signals 438 of the node 3 signals 422 transition from high 446 tolow 448, after which node 3 may send an idle signal 244 and data 242 onthe line 246.

FIG. 5 depicts a network 500 including a number of nodes (node 502, node504, node 506, node 508, and node 510), according to some embodiments.In this example, node 502 includes an amplifier, node 504 includes amicrophone, node 506 includes an antenna, node 508 includes a speaker,and node 510 includes a sensor. Further, in a first state 512, node 502,which is an amplifier, may be operating as a master node (node 0).Further, upon at least one event (e.g., an accident, which may besignaled by deployment of an airbag and/or failure (loss) of the masternode), network 500 may change to a second state 514. In the second state514, a node that in first state 512 was a slave node may assume the roleof a master node. In other words, for example, if node 502 fails and/oris disabled, node 506, which is an antenna in this case, may assume therole of a master node. Stated yet another way, upon loss of master node502, node 506 may be configured to operate as a fallback master node. Insome embodiments the node 506 may be designated as a backup master node516 during the first state 512. The designation of a backup master node516 may prevent all of the remaining operation nodes from attempting toassume mastership at the same time.

In some embodiments, in addition to switching a master node, a networkmay be reconfigured with a different set of nodes. For example, if node502 fails, node 506 may become the master node, and one or more othernodes may be disabled (e.g., to simply network 500 so that communicationto a ground station (e.g., after an accident) is simplified and/or morereliable). In the example shown in FIG. 5, the node 504 (microphone) andthe node 508 (speaker) may be disabled during the second state 514 tosimplify communication to a ground station.

As previously discussed, if the previous master node (node 502 duringthe first state 512) fails or is disabled, another node (e.g., node 506in the second state 514 of FIG. 5) may assume the role of the masternode. In some embodiments a failure of the previous master node may bedetected if a total number of beacon 238 signals the node 506 detectsduring a specific period of time falls below a predetermined range ofvalues. This predetermined range of values may be selected based on themaximum bus cycle length 326 (FIG. 3).

FIG. 6 depicts a system 600 including a network 602 (e.g., 10SPEnetwork) and a node 612 including a physical layer (PHY 700), a sublayer604, and a sensor 606. In some embodiments, one or more of the nodes ofFIG. 5 (e.g., node 502, node 504, node 506, node 508, and node 510) maybe implemented as shown for the node 612 of FIG. 6. For example,sublayer 604 may include a medium access control (MAC), amicrocontroller (μC), and/or firmware (FW). As non-limiting examples,PHY 700 may interface with network 602 via a medium-dependent interface(MDI 610), and PHY 700 may interface with sublayer 604 via a mediaindependent interface (MII 608).

FIG. 7 is a block diagram of an example of the PHY 700 of FIG. 6,according to some embodiments. FIG. 7 illustrates the PHY 700 operablycoupled to the line 246 (e.g., the shared transmission medium 106). ThePHY 700 includes a beacon counter 702 operably coupled to the line 246,an operational mode controller 704 operably coupled to the beaconcounter 702, and a beacon generator 706 operably coupled to theoperational mode controller 704 and to the line 246. The beacon counter702 is configured to receive beacon signals 708 generated by a masternode operably coupled to the line 246. In some embodiments, the beaconsignals 708 are generated by the PHY 700 while the PHY 700 is operatingas a master node of the network. In some embodiments, the beacon signals708 are generated by another node while the other node is operating as amaster node of the network and the PHY 700 is operating in a slave mode.The beacon counter 702 is configured to count a number of the beaconsignals 708, and report a beacon count/rate to the operational modecontroller 704 in a beacon count/rate signal 712. In some embodimentsthe beacon count/rate signal 712 may indicate a number of beacon signals708 detected (e.g., during a predetermined period of time). In someembodiments the beacon count/rate signal 712 may indicate a rate ofbeacon signals 708.

The operational mode controller 704 is configured to receive the beaconcount/rate signal 712 and determine whether the beacon count/rate fallswithin an acceptable range. The acceptable range may be determinedbased, at least in part, on a maximum bus cycle length (e.g., themaximum bus cycle length 326). For example, if the beacon count/rate isless than a number/rate that would be expected for maximum bus cyclelengths of each of the bus cycles, it may be determined that beaconsignals 708 are not being transmitted on the line 246 at times when thebeacon signals 708 should be transmitted. Accordingly, a minimum valueof an acceptable range for the beacon count/rate may be determined basedon the maximum bus cycle length.

While the PHY 700 is operating as the master node, the operational modecontroller 704 may be configured to terminate operation of the PHY 700as the master node responsive to an event. In some embodiments the eventmay include a failure in operation of the PHY 700 as the master node(e.g., responsive to a determination that the beacon count/rateindicated by the beacon count/rate signal 712 is outside of thepredetermined acceptable range of values). In some embodiments the eventmay include a vehicle collision or other event, which may be signaled tothe operational mode controller 704 with an event signal 710. In someembodiments the event signal 710 may include an airbag deploymentsignal. In some embodiments the event signal 710 may be provided to thePHY 700 from the line 246. In some embodiments the event signal 710 maybe provided to the PHY 700 directly (e.g., directly from an airbagdischarge device). The operational mode controller 704 is configured totransmit a master enable/disable signal 714 instructing the beacongenerator 706 to terminate transmission of the beacon signals 708 to theline 246.

While the PHY 700 is operating as a slave node, the operational modecontroller 704 may be configured to commence operation of the PHY 700 asthe master node responsive to a determination that the beacon/count rateindicated by the beacon count/rate signal 712 is outside of thepredetermined acceptable range of values. In some embodiments theoperational mode controller 704 may only commence operation of the PHY700 as the master node if the PHY 700 has been designated as a backupmaster node (e.g., by the current master node). For example, theoperational mode controller 704 is configured to transmit a masterenable/disable signal 714 instructing the beacon generator 706 tocommence transmission of the beacon signals 708 to the line 246. Thebeacon generator 706 is configured to receive the master enable/disablesignal 714, and transmit the beacon signals 708 to the line 246 or nottransmit the beacon signals 708 to the line 246 responsive to the masterenable/disable signal 714.

In some embodiments the operational mode controller 704 is configured totransmit an event signal 710 to the previous master node via the line246 before controlling the PHY 700 to take over as the master node. Theevent signal 710 is configured to indicate to the previous master nodethat an event was detected, and that the previous master node is notoperating properly as the master node. In some embodiments theoperational mode controller 704 may transmit the event signal 710 to allof the other nodes connected to the line 246. In some embodiments theevent signal 710 may indicate one or more of the previous master nodeand/or the other nodes that are to be disabled responsive to the event.In some embodiments the event signal 710 may indicate one of the nodesconnected to the line 246 to take over as a fallback master node to beready to take over as the master node responsive to a detection offailure or loss of the PHY 700 as master node. In some embodiments theoperational mode controller 704 may be configured to control the PHY 700to take over as the master node without transmitting an event signal710. In some embodiments the operational mode controller 704 may beconfigured to receive an event signal 710 transmitted by another node ofthe network. For example, if the PHY 700 is operating as the master nodeand another node of the network detects a failure of the PHY 700 as themaster node, the other node may transmit an event signal 710. In someembodiments the operational mode controller 704 is configured to disableoperation of the PHY 700 as the master node responsive to receiving theevent signal 710 by changing the state of the master enable/disablesignal 714. Also, in some embodiments, the operational mode controller704 may be configured to control the PHY 700 to operate as a fallbackmaster node responsive to receiving an event signal 710 designating thePHY 700 as the fallback master node.

In some embodiments at least a portion of the PHY 700 may be implementedusing electrical hardware (e.g., combinational logic). In someembodiments at least a portion of the PHY 700 may be implemented usingone or more processors. In some embodiments at least a portion of thePHY 700 may be implemented using firmware and/or software.

FIG. 8 is a flowchart illustrating an example method 800 of operating anetwork, such as a 10SPE network. Method 800 may be arranged inaccordance with at least one embodiment described in the presentdisclosure. Method 800 may be performed, in some embodiments, by adevice or system, such as network 500 (see FIG. 5), system 600 (see FIG.6), one or more of the components thereof, or another system or device.In these and other embodiments, method 800 may be performed based on theexecution of instructions stored on one or more non-transitorycomputer-readable media. Although illustrated as discrete blocks,various blocks may be divided into additional blocks, combined intofewer blocks, or eliminated, depending on the desired implementation.

Method 800 may begin at block 802, wherein an event in a network may bedetected. In some embodiments the event may be detected indirectly bydetecting an insufficient number of beacon signals over a period oftime. In some embodiments the event may be detected more directly (e.g.,via an airbag deployment signal). The event may include, for example, achange in an environment (e.g., a crash and/or an accident, loss of oneor more nodes, without limitation, that causes an unexpected beaconcount number) or other event that causes a detected rate or number ofbeacon 238 signals outside of a predetermined range of values. The eventmay be detected by a master node and/or a slave node. For example, a PHYof node 502 and/or a PHY of node 506 may detect a change in anenvironment or a rate or number of beacon 238 signals outside of apredetermined range of values. The change may include a count value ofthe number of detected beacon 238 signals not changing at an expectedrate. Further, in some embodiments, the event may be communicated to amaster node (e.g., master node 502 during first state 512 of FIG. 5).

At block 804, a beacon may be disabled responsive to the detected event,and method 800 may proceed to block 806. More specifically, for example,a beacon of the master node (e.g., master node 502 during first state512 of FIG. 5) may be disabled. For example, the beacon of the masternode may be disabled by the master node or another node. Morespecifically, for example, firmware of the master node may disable thebeacon of the master node.

At block 806, each node in a network may be resynced, and method 800 mayproceed to block 808. More specifically, for example, each PHY of eachnode in the network may enter a PLCA RESYNC state to resync each node inthe network.

At block 808, a slave node (e.g., a fallback master node) may assumemastership of the network. In other words, the master (“mastership”) maybe changed from one node to another node. For example, slave node 506(see FIG. 5) may assume a master role. Yet more specifically, forexample, firmware of the slave node may set its PLCA ID to 0 to assumemastership.

Modifications, additions, or omissions may be made to method 800 withoutdeparting from the scope of the present disclosure. For example, theoperations of method 800 may be implemented in differing order.Furthermore, the outlined operations and actions are only provided asexamples, and some of the operations and actions may be optional,combined into fewer operations and actions, or expanded into additionaloperations and actions without detracting from the essence of thedisclosed embodiment.

FIG. 9 is a flowchart illustrating an example method 900 of operating anetwork node, according to some embodiments. In block 902, method 900detects an event in a wired local area network including physical levelcollision avoidance, the wired local area network including a line of ashared transmission medium. In block 904, method 900 disables a beacontransmitted by the network node, so as to disable operation of thenetwork node as the master node, in response to the event if the networknode is operating as the master node of the wired local area network. Inblock 906, method 900 enables the beacon to be transmitted by thenetwork node, so as to operate the network node as a master node of thewired local area network, in response to the event if the network nodeis operating as a slave node (e.g., a fallback master node). In someembodiments the network node may take over operation as the master nodeand transmit the beacon in indirect response to the event. For example,the network node may take over operation as the master node responsiveto a determination that the previous master node is not providing beaconsignals at a sufficient rate (e.g., a count of beacons is lower thanexpected).

FIG. 10 depicts a vehicle 1000 (e.g., a truck, a bus, a ship, and/or anaircraft) including a network 1002 (e.g., a 10SPE network) having anumber of nodes (e.g., amplifier(s), microphone(s), antenna(s),speaker(s), sensor(s), etc.). According to some embodiments, network1002, which may also be referred to as a “vehicle network,” includes aphysical level collision avoidance (PLCA) sublayer. Further, in someembodiments, a first node (e.g., an amplifier) may be configured tooperate as a master of the 10SPE network. In addition, a second node(e.g., an antenna) may be configured to assume mastershipresponsibilities from the first node in response to a detected event(e.g., a crash/accident or other master node disabling event involvingvehicle 1000).

As described herein, one or more slaves (e.g., slave nodes) of a networkmay detect a failure of a PLCA master (e.g., by monitoring beacon countand/or other parameters (e.g., signal quality)). Further, a designatedslave (e.g., a fallback master) may become (e.g., takeover) as themaster (e.g., in response to failure of the master). More specifically,for example, based on a beacon count and possibly other statusinformation (e.g., signal quality), a master of a network may beswitched from one node to another node. Further, in some embodiments,the original master may be reconfigured as a slave node. As a morespecific example, during a crash (e.g., involving a vehicle including anetwork), a master node may stop sending beacons, and an eCall node maydetect, for example, a lack of change in beacon count, and take over asthe master node.

FIG. 11 is a block diagram of a computing device 1100 that may be usedin some embodiments. The computing device 1100 includes one or moreprocessors 1102 (sometimes referred to herein as “processor processors1102”) operably coupled to one or more data storage devices (sometimesreferred to herein as “storage 1104”). The storage 1104 includescomputer-readable instructions (e.g., software, firmware) storedthereon. The computer-readable instructions are configured to instructthe processors 1102 to perform operations of embodiments disclosedherein. For example, the computer-readable instructions may beconfigured to instruct the processors 1102 to perform at least a portionor a totality of the method 800 of FIG. 8 and/or the method 900 of FIG.9. As another example, the computer-readable instructions may beconfigured to instruct the processors 1102 to perform at least a portionor a totality of the operations discussed for the nodes (e.g., node 502,node 504, node 506, node 508, or node 510) of FIG. 5; the network 602,the PHY 700, the sublayer 604, or the sensor 606 of FIG. 6; the beaconcounter 702, the operational mode controller 704, the beacon generator706 of FIG. 7; or the network 1002 of FIG. 10. As a specific,non-limiting example, the computer-readable instructions may beconfigured to instruct the processors 1102 to disable a master node(e.g., disable itself) responsive to detection of an event correspondingto failure of the master node. As another specific, non-limitingexample, the computer-readable instructions may be configured toinstruct the processors 1102 to control a physical layer device (e.g.,PHY 700 of FIG. 6 and FIG. 7) to assume the role of master noderesponsive to detecting that an event corresponding to failure of themaster node.

Various embodiments of the present disclosure may improving 10SPErobustness by detecting PLCA master failures and deploying fallbackmasters (e.g., for recovery and/or for eCall support)

As used in the present disclosure, the terms “module” or “component” mayrefer to specific hardware implementations configured to perform theactions of the module or component and/or software objects or softwareroutines that may be stored on and/or executed by general purposehardware (e.g., computer-readable media, processing devices, etc.) ofthe computing system. In some embodiments, the different components,modules, engines, and services described in the present disclosure maybe implemented as objects or processes that execute on the computingsystem (e.g., as separate threads). While some of the system and methodsdescribed in the present disclosure are generally described as beingimplemented in software (stored on and/or executed by general purposehardware), specific hardware implementations or a combination ofsoftware and specific hardware implementations are also possible andcontemplated.

Terms used in the present disclosure and especially in the appendedclaims (e.g., bodies of the appended claims) are generally intended as“open” terms (e.g., the term “including” should be interpreted as“including, but not limited to,” the term “having” should be interpretedas “having at least,” the term “includes” should be interpreted as“includes, but is not limited to,” etc.).

Additionally, if a specific number of an introduced claim recitation isintended, such an intent will be explicitly recited in the claim, and inthe absence of such recitation no such intent is present. For example,as an aid to understanding, the following appended claims may containusage of the introductory phrases “at least one” and “one or more” tointroduce claim recitations. However, the use of such phrases should notbe construed to imply that the introduction of a claim recitation by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more”); the same holds true for the use of definite articlesused to introduce claim recitations.

In addition, even if a specific number of an introduced claim recitationis explicitly recited, those skilled in the art will recognize that suchrecitation should be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, means at least two recitations, or two or more recitations).Furthermore, in those instances where a convention analogous to “atleast one of A, B, and C, etc.” or “one or more of A, B, and C, etc.” isused, in general such a construction is intended to include A alone, Balone, C alone, A and B together, A and C together, B and C together, orA, B, and C together, etc.

Further, any disjunctive word or phrase presenting two or morealternative terms, whether in the description, claims, or drawings,should be understood to contemplate the possibilities of including oneof the terms, either of the terms, or both terms. For example, thephrase “A or B” should be understood to include the possibilities of “A”or “B” or “A and B.”

EXAMPLES

A non-exhaustive, non-limiting list of example embodiments follows. Noteach of the example embodiments listed below are individually indicatedas being combinable with all others of the example embodiments listedbelow and embodiments discussed above. It is intended, however, thatthese example embodiments are combinable with all other exampleembodiments and embodiments discussed above unless it would be apparentto one of ordinary skill in the art that the embodiments are notcombinable.

Example 1

A method, comprising: detecting an event in a 10SPE network includingphysical level collision avoidance (PLCA); disabling a beacon of a firstnode of the 10SPE network operating as a master of the 10SPE network inresponse to the event; and enabling a second node to operate as themaster of the 10SPE network.

Example 2

The method of Example 1, wherein detecting the event comprises:monitoring a beacon count for the first node; and determining the firstnode has failed in response to the beacon being less than an expectedcount.

Example 3

The method according to any one of Examples 1 and 2, wherein disablingcomprises disabling, via firmware of the first node, the beacon of thefirst node.

Example 4

The method according to any one of Examples 1-3, further comprisingcommunicating the event to the first node.

Example 5

The method according to any one of Examples 1-4, wherein disabling thebeacon of the first node comprises disabling the beacon of an amplifier.

Example 6

The method of Example 5, wherein enabling the second node comprisesenabling an antenna to operate as the master.

Example 7

The method according to any one of Examples 1-6, further comprisingdisabling the first node and at least one other node of the 10SPEnetwork in response to the event.

Example 8

A method, comprising: counting a number of beacons sent by a nodeoperating as a master of a 10SPE network including physical levelcollision avoidance (PLCA); and in response to the number of beaconssent by the node being less than a threshold number, changing the masterto another node of the 10SPE network.

Example 9

The method of Example 8, wherein counting the number of beacons sent bythe node operating as the master comprises counting the number ofbeacons sent by an amplifier.

Example 10

The method according to any one of Examples 8 and 9, wherein changingthe master to another node of the 10SPE network comprises changing themaster to an antenna of the 10SPE network.

Example 11

The method of according to any one of Examples 8-10, further comprising,in response to the number of beacons sent by the node being less than athreshold number, disabling the node.

Example 12

The method of Example 11, further comprising, in response to the numberof beacons sent by the node being less than the threshold number,disabling at least a third node of the 10SPE network.

Example 13

The method according to any one of Examples 8-12, wherein changing themaster to another node of the 10SPE network comprises setting a PCLAidentification (ID) of the another node to 0.

Example 14

A 10SPE network including physical level collision avoidance (PLCA),comprising: a first node configured to operate as a master of the 10SPEnetwork; and a second node configured to assume mastershipresponsibilities from the first node in response to detecting an event.

Example 15

The 10SPE network of Example 14, wherein at least one of the first nodeand the second node is configured to cause one or more other nodes ofthe 10SPE network to go offline in response to the event.

Example 16

The 10SPE network according to any one of Examples 14 and 15, furthercomprising one or more other nodes configured to go offline in responseto the event.

Example 17

The 10SPE network according to any one of Examples 14-16, wherein thesecond node is configured to count a number of beacons sent by the firstnode.

Example 18

The 10SPE network of Example 17, wherein the event is in response to thenumber of beacons sent by the first node being less than an expectednumber of beacons.

Example 19

The 10SPE network according to any one of Examples 14-18, wherein theevent comprises at least one of a failure and a crash.

Example 20

A vehicle including a 10SPE network including physical level collisionavoidance (PLCA), the vehicle comprising: an amplifier configured tooperate as a master of the 10SPE network; and an antenna configured toassume mastership responsibilities from the amplifier in response todetecting an event.

Example 21

The vehicle of Example 20, wherein the event comprises a crash involvingthe vehicle.

Example 22

A physical layer device for a network node, the physical layer devicecomprising: a beacon counter operably coupled to a line of a sharedtransmission medium of a wired local area network including physicallevel collision avoidance, the beacon counter configured to count beaconsignals on the line and determine a beacon count over a predeterminedtime period or a beacon rate of the beacon signals; and an operationalmode controller configured to: determine whether the determined beaconcount or the determined beacon rate falls within a predeterminedacceptable range of values; and control the physical layer device totake over operation as a master node of the wired local area networkresponsive to a determination that the determined beacon count or thedetermined beacon rate falls outside of the predetermined acceptablerange of values.

Example 23

The physical layer device of Example 22, wherein the operational modecontroller is configured to control the physical layer device to takeover operation as the master node only if the physical layer device hasbeen designated as a fallback master node.

Example 24

The physical layer device according to any one of Examples 22 and 23,wherein the operational mode controller is further configured to disablea beacon transmitted by the network node to disable operation of thenetwork node as the master node responsive to an event.

Example 25

The physical layer device of Example 24, wherein the event includes avehicle collision.

Example 26

The physical layer device according to any one of Examples 22-25,wherein a minimum value of the predetermined acceptable range of valuesis determined based on a maximum bus cycle length of bus cycles on theline.

Example 27

A method of operating a network node, the method comprising: detectingan event in a wired local area network including physical levelcollision avoidance, the wired local area network including a line of ashared transmission medium; and enabling the beacon to be transmitted bythe network node to operate the network node as a master node of thewired local area network in response to a determination that a beaconcount over a predetermined time period or a beacon rate of a beaconsignal is less than a predetermined minimum value if the network node isoperating as a slave node.

Example 28

The method of Example 27, further comprising disabling a beacontransmitted by the network node to disable operation of the network nodeas the master node in response to the event if the network node isoperating as the master node of the wired local area network.

Example 29

The method of Example 28, further comprising disabling at least one noderesponsive to disabling operation of the network node as the masternode.

Example 30

The method according to any one of Examples 28 and 29, wherein the eventcomprises receipt of an event signal configured to signal the event.

Example 31

The method according to any one of Examples 28-30, wherein disabling thebeacon comprises disabling the beacon via firmware of the network node.

Example 32

The method according to any one of Examples 27-31, wherein enabling thebeacon to be transmitted by the network node to operate the network nodeas the master node in response to the event comprises transitioning fromoperating the network node as the slave node to operating the networknode as the master node only if the network node was previouslydesignated as a fallback network node.

Example 33

The method of Example 32, wherein transitioning from operating thenetwork node as the slave node to operating the network node as themaster node comprises transitioning from operating the network node asthe slave node to operating the network node as the master node withoutintervention from a previous master node.

Example 34

The method according to any one of Examples 27-33, wherein detecting theevent comprises: monitoring a beacon signal on the line to detect abeacon count or a beacon rate on the line; and determining that themaster node has failed in response to the detected beacon count or thedetected beacon rate falling outside of a predetermined acceptable rangeof values.

Example 35

The method of Example 34, wherein the detected beacon count or thedetected beacon rate falling outside of a predetermined acceptable rangeof values comprises the detected beacon count or the detected beaconrate exceeding a maximum value of the predetermined acceptable range ofvalues.

Example 36

The method of Example 34, wherein the detected beacon count or thedetected beacon rate falling outside of a predetermined acceptable rangeof values comprises the detected beacon count or the detected beaconrate falling below a minimum value of the predetermined acceptable rangeof values.

Example 37

The method according to any one of Examples 27-36, further comprisingcommunicating the event to a previous master node responsive todetecting the event.

Example 38

The method according to any one of Examples 27-37, further comprisingdisabling a previous master node and at least one other node of thewired local area network in response to the event.

Example 39

A wired local area network (WLAN) including physical level collisionavoidance, comprising: a line of a shared transmission medium; a firstnode operably coupled to the line, the first node configured to operateas a master of the WLAN; and a second node configured to assumemastership responsibilities from the first node in response to detectingan event.

Example 40

The WLAN of Example 39, wherein the at least one of the first node andthe second node is configured to disable one or more other nodes of theWLAN in response to the event.

Example 41

The WLAN according to any one of Examples 39 and 40, wherein the secondnode is configured to count a number of beacons sent by the first node.

Example 42

The WLAN of Example 41, wherein the event is in response to the numberof beacons sent by the first node over a predetermined time period or arate of beacons falling outside of a predetermined acceptable range ofvalues.

Example 43

The WLAN according to any one of Examples 39-42, wherein the eventcomprises at least one of a failure of the first node and a crash of avehicle including the first node.

Example 44

A vehicle including a wired local area network including physical levelcollision avoidance, the vehicle comprising: an amplifier configured tooperate as a master of the WLAN, the WLAN including a sharedtransmission medium; and an antenna configured to assume mastershipresponsibilities from the amplifier in response to detecting an event.

Example 45

The vehicle of Example 44, wherein the event comprises a crash involvingthe vehicle.

While the present disclosure has been described herein with respect tocertain illustrated embodiments, those of ordinary skill in the art willrecognize and appreciate that the present invention is not so limited.Rather, many additions, deletions, and modifications to the illustratedand described embodiments may be made without departing from the scopeof the invention as hereinafter claimed along with their legalequivalents. In addition, features from one embodiment may be combinedwith features of another embodiment while still being encompassed withinthe scope of the invention as contemplated by the inventor.

What is claimed is:
 1. A physical layer device for a network node, thephysical layer device comprising: a beacon counter operably coupled to aline of a shared transmission medium of a wired local area networkincluding physical level collision avoidance, the beacon counterconfigured to count beacon signals on the line and determine a beaconcount over a predetermined time period, or a beacon rate of the beaconsignals; and an operational mode controller configured to: determinewhether the determined beacon count or the determined beacon rate fallswithin a predetermined acceptable range of values; and control thephysical layer device to take over operation as a master node of thewired local area network responsive to a determination that thedetermined beacon count or the determined beacon rate falls outside ofthe predetermined acceptable range of values.
 2. The physical layerdevice of claim 1, wherein the operational mode controller is configuredto control the physical layer device to take over operation as themaster node only if the physical layer device has been designated as afallback master node.
 3. The physical layer device of claim 1, whereinthe operational mode controller is further configured to disable abeacon transmitted by the network node to disable operation of thenetwork node as the master node responsive to an event.
 4. The physicallayer device of claim 3, wherein the event includes a vehicle collision.5. The physical layer device of claim 1, wherein a minimum value of thepredetermined acceptable range of values is determined based on amaximum bus cycle length of bus cycles on the line.
 6. A method ofoperating a network node, the method comprising: detecting an event in awired local area network including physical level collision avoidance,the wired local area network including a line of a shared transmissionmedium; and enabling the beacon to be transmitted by the network node tooperate the network node as a master node of the wired local areanetwork in response to a determination that a beacon count over apredetermined time period or a beacon rate of a beacon signal is lessthan a predetermined minimum value if the network node is operating as aslave node.
 7. The method of claim 6, further comprising disabling abeacon transmitted by the network node to disable operation of thenetwork node as the master node in response to the event if the networknode is operating as the master node of the wired local area network. 8.The method of claim 7, further comprising disabling at least one noderesponsive to disabling operation of the network node as the masternode.
 9. The method of claim 7, wherein the event comprises receipt ofan event signal configured to signal the event.
 10. The method of claim7, wherein disabling the beacon comprises disabling the beacon viafirmware of the network node.
 11. The method of claim 6, whereinenabling the beacon to be transmitted by the network node to operate thenetwork node as the master node in response to the event comprisestransitioning from operating the network node as the slave node tooperating the network node as the master node only if the network nodewas previously designated as a fallback network node.
 12. The method ofclaim 11, wherein transitioning from operating the network node as theslave node to operating the network node as the master node comprisestransitioning from operating the network node as the slave node tooperating the network node as the master node without intervention froma previous master node.
 13. The method of claim 6, wherein detecting theevent comprises: monitoring a beacon signal on the line to detect abeacon count or a beacon rate on the line; and determining that themaster node has failed in response to the detected beacon count or thedetected beacon rate falling outside of a predetermined acceptable rangeof values.
 14. The method of claim 13, wherein the detected beacon countor the detected beacon rate falling outside of a predeterminedacceptable range of values comprises the detected beacon count or thedetected beacon rate exceeding a maximum value of the predeterminedacceptable range of values.
 15. The method of claim 13, wherein thedetected beacon count or the detected beacon rate falling outside of apredetermined acceptable range of values comprises the detected beaconcount or the detected beacon rate falling below a minimum value of thepredetermined acceptable range of values.
 16. The method of claim 6,further comprising communicating the event to a previous master noderesponsive to detecting the event.
 17. The method of claim 6, furthercomprising disabling a previous master node and at least one other nodeof the wired local area network in response to the event.
 18. A wiredlocal area network (WLAN) including physical level collision avoidance,comprising: a line of a shared transmission medium; a first nodeoperably coupled to the line, the first node configured to operate as amaster of the WLAN; and a second node configured to assume mastershipresponsibilities from the first node in response to detecting an event.19. The WLAN of claim 18, wherein the at least one of the first node andthe second node is configured to disable one or more other nodes of theWLAN in response to the event.
 20. The WLAN of claim 18, wherein thesecond node is configured to count a number of beacons sent by the firstnode.
 21. The WLAN of claim 20, wherein the event is in response to thenumber of beacons sent by the first node over a predetermined timeperiod, or a rate of beacons, falling outside of a predeterminedacceptable range of values.
 22. The WLAN of claim 18, wherein the eventcomprises at least one of a failure of the first node and a crash of avehicle including the first node.
 23. A vehicle including a wired localarea network including physical level collision avoidance, the vehiclecomprising: an amplifier configured to operate as a master of the WLAN,the WLAN including a shared transmission medium; and an antennaconfigured to assume mastership responsibilities from the amplifier inresponse to detecting an event.
 24. The vehicle of claim 23, wherein theevent comprises a crash involving the vehicle.